Controlling a Gangway being Used to Provide Bridge Between Two Vessel at Sea that are Moving in Respect to Each Other Due to Sea Motion
Short gangways are in use all over the world as a convenient and practical access method from a vessel to rig, wind turbine, shore, quay and other structures. Different design options are available, where length and other parameters are adapted by designers and suppliers to accommodate customers inputs and requests. Typically, the gangways are moveable in several degrees of freedom, using hydraulic or other types of actuators, and are operated by a skilled operator for safely establishing a bridge between vessels, or between vessel and a fixed installation, at sea or in harbour like environments. When operated, the functions of the gangway are typically controlled by the operator using joysticks, which may be part of a portable remote control unit or a fixed control unit located in a control cabin for the gangway.
Numerous such gangways and evacuation systems have been installed over the course of years, and gangways between vessels, or between vessel and a fixed installations have a been operating in periods counted in decades. Typical uses are for purpose built “Walk to Work” maintenance vessels and “Subsea Support” vessels, outfitted for offshore inspections, maintenance and repairs, in addition to general subsea work. These kinds of vessels equipment could also include long-reach offshore cranes and, vessels may be prepared for skid and ROV installations.
Gangways are in use all over the world as a critical and practical access method from a vessel to platforms, rigs, wind turbines and other structures in or at sea. Today, the wind turbine crew access operation is done by jamming the vessel bow against the wind turbine tower, which clearly is a risky operation.
Although gangways could be made in seawaterproof aluminium, making for a durable and lightweight constructions that is highly maouverable, there is always a risk that the operator may not be able to compensate for sea motion and other effects of the environment when attempting to manouver the gangway for establishing a bridge connection between vessels, or between vessel and a fixed installation. Missing an opportunity to establish the gangway bridge connection may result in cancellation of an important mission, which could lead to very high costs and risk of having to shut down the operations of an off-shore installation for lack of maintenance or lack of new crew. Accordingly, there is a need for a an active control solution for a gangway that will ensure safe, reliable and accurate motion compensation in the manouvering of the gangway that will allow establishing of a gangway bridge connection between vessels or between vessel and a fixed installation also under conditions when manual control may not be safely relied on.